In the sport of baseball the position of pitcher requires the throwing or "pitching" of a ball so that it passes over a plate beside which a participant in the position of batter stands and attempts to strike the ball with a baseball bat. Rules governing the sport of baseball require that the pitcher throw the ball from an upraised portion of the playing field called a pitcher's mound. The rules further require that for a pitch to be valid, the pitcher must have one foot in contact with a slab installed at the pitcher's position at the moment of delivery. This slab is commonly referred to in the sport as a "rubber". The size and relative disposition of such elements as the plate, rubber and pitcher's mound are specified in the rules. It is customary but not necessary to provide a recess or "divot" adjacent the edge of the rubber facing the plate for the pitcher's toes at the moment of delivery.
Aside from the exact shape of the mound required by the rules, the shape of the pitching mound has considerable effect on the pitcher's action. As he pitches, his leading foot will land at a position significantly lower than the trailing foot. Also, due to the height of the mound, the pitcher is effectively pitching down to the batter. For this reason, pitchers develop actions dependant on the shape of the mound. During winter, it is common for baseball players to practice indoors in a gymnasium or the like. However, to the Applicant's knowledge, at the present time there is no readily available device for simulating a pitcher's mound. Consequently, indoor pitching practice is often carried out on a level floor. This is awkward for the pitcher, and can detrimentally effect his pitching style.
Portable pitcher's mounds have been developed which enable the sport of baseball to be played on flat fields, which can also be used to convert a regular sized baseball field to reduced size for junior and little league games by placing the pitcher's mound the proper distance from home plate for a youthful player and which furthermore allow the pitcher to practice indoors during inclement weather. Examples of such portable pitcher's mounds can be found in the following U.S. Patents:
U.S. Pat. No. 2,156,469 (Boltz)
U.S. Pat. No. 3,703,285 (Perry)
U.S. Pat. No. 4,063,729 (Hollaway)
U.S. Pat. No. 4,306,718 (Goeders)
Some of the earlier designs for portable pitcher's mounds have the disadvantage of inadequate rigidity which allows them to flex beneath the pitcher's feet and thus interfere with the accuracy of the throw. Also, many of the earlier designs are difficult to transport as they are too large to fit into the luggage compartment of an automobile. Those prior designs which do fit into the luggage compartment of an automobile are limited in size by the dimensions of the average automobile luggage compartment. As pitcher's mounds can be on the order of ten feet in diameter, aside from the portability considerations, storage can be a problem. Since portable mounds are often used indoors in gymnasiums or sports halls, they must be capable of being moved and stored to allow other activities and sports.
A further disadvantage of some of the earlier designs for portable pitcher's mounds is that their surface is much harder than that of permanent mounds which ordinarily are made of earth or clay. It is desirable that a portable or artificial mound simulate the behaviour of a clay mound, with respect to both how the ball bounces off it and how it feels to the pitcher. These prior pitcher's mounds therefore create a hazard in that when struck by a baseball, they do not absorb as much of the impact as would a clay or earth mound so that the baseball may be deflected up to potentially injure the pitcher. The possibility of such injury is greater in junior and little league games where the pitcher has less experience and is less likely to take appropriate action.
U.S. Pat. No. 4,063,729 attempts to overcome this hazard by shaping the edge of the pitcher's mound facing the batter so as to deflect the ball away from the pitcher. A disadvantage of providing such a deflecting edge is that the bounce of the baseball striking this edge would be erratic and therefore not representative of the result that would be obtained from striking a clay or earth mound.
It is desirable to have a pitching mound complete with rubber and divot, of knock-down construction, which is portable and easily assembled to provide a rigid structure which will not flex beneath the pitcher's feet in such a manner as to impair his throw. It is further desirable that the surface of the mound provide a good grip for the pitcher's feet and also absorb some of the impact when struck by a baseball so as not to deflect the ball up at the pitcher to potentially injure the pitcher.